Sheet manufacturing method

ABSTRACT

A sheet manufacturing method includes: a defibrating step of defibrating a raw material containing a fiber in air; a mixing step of mixing a defibrated material defibrated in the defibrating step and a resin in air; a web forming step of forming a web by accumulating the mixture mixed in the mixing step on a moving body; a transporting step of transporting the web; a sheet forming step of forming a sheet from the web; a setting step of setting a thickness of the sheet; and a control step of controlling a moving speed of the moving body and a transporting speed of the web in the transporting step, in accordance with the thickness of the sheet set in the setting step.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 15/779,632 filed on May 29, 2018, which is a U.S. National stageapplication of International Patent Application No. PCT/JP2016/084020,filed on Nov. 17, 2016, which claims priority under 35 U.S.C. § 119(a)to Japanese Patent Application No. 2015-232961, filed in Japan on Nov.30, 2015. The entire disclosures of U.S. application Ser. No. 15/779,632and Japanese Patent Application No. 2015-232961 are hereby incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates to a sheet manufacturing apparatus, acontrol method of the sheet manufacturing apparatus, and a sheetmanufacturing method.

BACKGROUND ART

Accumulating a fiber-like material and causing a bonding force betweenthe accumulated fibers to obtain a sheet-like or film-like formed bodyhas been performed for a long time. Typical examples thereof includemanufacturing paper by pulp molding (paper-forming) using water. Even inpresent times, pulp molding is widely used as an example of a method ofmanufacturing paper. The paper manufactured by pulp molding generallyincludes a structure by cellulose fibers derived from wood or the likebeing entangled with one another, and being partially bonded to oneanother by a binder (paper strengthening agent (such as a starch pasteand a water-soluble resin)).

According to the pulp molding, it is possible for the fibers to beaccumulated in a state where uniformity is favorable, and, in a casewhere a paper strengthening agent is used in the bonding between fibers,it is possible for the paper strengthening agent to be dispersed(distributed) in a state where the uniformity in the paper surface isgood. However, because the pulp molding is a wet method, it is necessaryto use large volumes of water, and the necessity of dewatering anddrying, or the like, arises after forming the paper, and therefore theenergy or time consumed is extremely large. It is necessary to suitablyprocess the water used as waste water. Accordingly, it is difficult torespond to modern demands for energy savings, environmental protection,and the like. The apparatuses used in pulp molding frequently need largescale utilities such as water, power, and drainage facilities, and sizereductions are difficult. From this viewpoint, there is an expectationof methods, referred to as dry methods that use no or almost no water aspaper manufacturing methods in place of pulp molding.

As such a method, for example, Japanese Unexamined Patent ApplicationPublication No. 2012-144826 discloses a paper recycling apparatus whichincludes a dry defibrating unit, and accumulates and forms fibrillatedfibers.

In a paper recycling apparatus disclosed in Japanese Unexamined PatentApplication Publication No. 2012-144826, the thickness of the paper tobe manufactured is measured by a sensor, and depending on the detectionresult, a speed of a mesh belt for accumulating fibers and a feedingspeed of paper (raw material) to be supplied to an apparatus areadjusted, and the thickness of the paper to be manufactured is adjusted.

However, in the apparatus disclosed in Japanese Unexamined PatentApplication Publication No. 2012-144826, in a case of increasing thethickness of the paper to be manufactured, the moving speed of the meshbelt is decreased, and further, control for increasing an insertionspeed of the paper (raw material) is performed, as necessary. In thismanner, in a case where a supply amount is increased by increasing thefeeding speed of the paper so as to increase the thickness of the paperto be manufactured, each constituent part that performs a process suchas coarse crushing, defibration, and deinking needs to have sufficientprocessing capacity to handle a large amount of paper (raw material).For this reason, there is a problem in that each of the constituentparts is increased in size and power consumption is increased. Also,when the moving speed of the mesh belt is decreased, the fibersaccumulated by a transport roller positioned on the downstream side arepulled, and thus are broken or thinned, and thereby it is difficult tostably manufacture paper in some cases.

An object of some aspects of the invention is to provide a sheetmanufacturing apparatus, a control method of the sheet manufacturingapparatus, and a sheet manufacturing method which are capable of stablymanufacturing sheets having different thicknesses while maintaining acompact and power saving apparatus configuration.

SUMMARY

The present invention has been made to solve at least a part of theabove problems, and can be realized as the following aspects orapplication examples.

According to an aspect of the invention, there is provided a sheetmanufacturing apparatus including a defibrating unit that defibrates araw material containing a fiber in air; a mixing unit that mixes adefibrated material defibrated by the defibrating unit and a resin inair; a web forming unit that forms a web by accumulating the mixturemixed by the mixing unit on a moving body; a transporting unit thattransports the web; a sheet forming unit that forms a sheet from theweb; a setting unit that sets a thickness of the sheet; and a controllerthat controls a moving speed of the moving body and a transporting speedof the web transported by the transporting unit, in accordance with thethickness of the sheet set by the setting unit.

According to the sheet manufacturing apparatus, both of the moving speedof the moving body and the transporting speed of the transporting unitare controlled in accordance with the thickness of the sheet. Therefore,in a case where the thickness of the sheet to be manufactured ischanged, tension is more hardly applied to the web transported betweenthe moving body and the transporting unit, and thereby it is less likelythat the web is pulled, and thus is broken or thinned. With this, it ispossible to stably manufacture the sheet.

In the sheet manufacturing apparatus according to the invention, thecontroller may change the moving speed of the moving body and thetransporting speed of the transporting unit at the same time.

According to the sheet manufacturing apparatus, even in a case where thethickness of the sheet to be manufactured is changed, it is difficult tocause a transport jam to occur, and it is possible to stably manufacturethe sheet.

In the sheet manufacturing apparatus according to the invention, thecontroller may decrease the moving speed of the moving body afterdecreasing the transporting speed of the transporting unit whendecreasing the moving speed of the moving body and the transportingspeed of the transporting unit.

According to the sheet manufacturing apparatus, in a case where thethickness of the sheet to be manufactured is changed (set) so as to beincreased, tension is more hardly applied to the web, and thereby it isless likely that the web is broken or thinned.

In the sheet manufacturing apparatus according to the invention, thetransporting unit includes a first roller pair and a second roller pairthat is positioned on the downstream side of the first roller pair, inwhich the controller may decrease the transporting speed of the firstroller pair after decreasing the transporting speed of the second rollerpair when decreasing the transporting speed of the transporting unit.

According to the sheet manufacturing apparatus, in a case where thethickness of the sheet to be manufactured is set (changed) to bethicken, it is possible to more stably manufacture the sheet.

In the sheet manufacturing apparatus according to the invention, thetransporting speed of the transporting unit may be increased afterincreasing the moving speed of the moving body when increasing themoving speed of the moving body and the transporting speed of thetransporting unit.

According to the sheet manufacturing apparatus, in a case where thethickness of the sheet to be manufactured is set (changed) so as to bethinned, tension is hardly applied to the web, and thereby it is lesslikely that the web is pulled, and thus is broken or thinned. With this,it is possible to stably manufacture the sheet.

In the sheet manufacturing apparatus according to the invention, thetransporting unit includes a first roller pair and a second roller pairthat is positioned on the downstream side of the first roller pair, inwhich the controller may increase the transporting speed of the secondroller pair after increasing the transporting speed of the first rollerpair when increasing the transporting speed of the transporting unit.

According to the sheet manufacturing apparatus, in a case where thethickness of the sheet to be manufactured is set (changed) so as to bethinned, it is possible to more stably manufacture the sheet.

In the sheet manufacturing apparatus according to the invention, thecontroller may stepwisely change each of the moving speed of the movingbody and the transporting speed of the transporting unit.

According to the sheet manufacturing apparatus, since the thickness ofthe web is stepwisely changed, for example, insertion into the rollerpair becomes smooth, and thereby even in a case where the thickness ofthe sheet to be manufactured is changed, it is difficult to cause atransport jam to occur, and it is possible to stably manufacture thesheet.

In the sheet manufacturing apparatus according to the invention, thecontroller may linearly change each of the moving speed of the movingbody and the transporting speed of the transporting unit.

According to the sheet manufacturing apparatus, since the thickness ofthe web is gradually changed, for example, insertion into the rollerpair becomes smooth, and thereby even in a case where the thickness ofthe sheet to be manufactured is changed, it is difficult to cause atransport jam to occur, and it is possible to stably manufacture thesheet.

The sheet manufacturing apparatus according to the invention furtherincludes a supplying unit that supplies an additive agent to the mixingunit, in which the controller may change a supplying amount of theadditive agent supplied by the supplying unit in accordance with thethickness of the sheet set by the setting unit.

According to the sheet manufacturing apparatus, even in a case where thethickness of the sheet to be manufactured is changed, it is possible tostabilize the amount of the additive agent (abundance) in the sheet tobe manufactured. With this, the mechanical strength of the sheet to bemanufactured can be stabilized.

The sheet manufacturing apparatus according to the invention furtherincludes a suction unit that suctions the mixture onto the moving body,in which controller may change a suction force of the suction unit inaccordance with the thickness of the sheet set by the setting unit.

According to the sheet manufacturing apparatus, even in a case where thethickness of the sheet to be manufactured is changed, it is possible tostabilize the amount of the additive agent (abundance) in the sheet tobe manufactured. With this, the mechanical strength of the sheet to bemanufactured can be stabilized.

In the sheet manufacturing apparatus according to the invention, thesetting unit is capable of setting the thickness of the sheet to a firstthickness and a second thickness larger than the first thickness, andthe controller may stop the sheet manufacturing apparatus after settingthe moving speed of the moving body and the transporting speed of thetransporting unit to a speed in accordance with the first thickness.

According to the sheet manufacturing apparatus, since the thickness ofthe web remaining between a pair of rollers at the time of stop is thefirst thickness which is relatively thin, the web is less likely to beloosened, and broken under its own weight.

According to another aspect of the invention, there is provided acontrol method of a sheet manufacturing apparatus which includes adefibrating unit that defibrates a raw material containing a fiber inair; a mixing unit that mixes a defibrated material defibrated by thedefibrating unit and a resin in air; a web forming unit that forms a webby accumulating the mixture mixed by the mixing unit on a moving body; atransporting unit that transports the web; a sheet forming unit thatforms a sheet from the web; and a setting unit that sets a thickness ofthe sheet, the method including controlling a moving speed of the movingbody and a transporting speed of the web transported by the transportingunit, in accordance with the thickness of the sheet set by the settingunit.

According to the control method of the sheet manufacturing apparatus,both of the moving speed of the moving body and the transporting speedof the web are controlled in accordance with the thickness of the sheet.Therefore, when the thickness of the sheet to be manufactured ischanged, tension is more hardly applied to the web to be transported,and thereby it is less likely that the web is pulled, and thus is brokenor thinned. With this, it is possible to stably manufacture the sheet.

According to still another aspect of the invention, there is provided asheet manufacturing method including a defibrating step of defibrating araw material containing a fiber in air; a mixing step of mixing adefibrated material defibrated in the defibrating step and a resin inair; a web forming step of forming a web by accumulating the mixturemixed in the mixing step on a moving body; a transporting step oftransporting the web; a sheet forming step of forming a sheet from theweb; a setting step of setting a thickness of the sheet; and a controlstep of controlling a moving speed of the moving body and a transportingspeed of the web in the transporting step, in accordance with thethickness of the sheet set in the setting step.

According to the sheet manufacturing method, both of the moving speed ofthe moving body in the web forming step and the transporting speed ofthe web in the transporting step are controlled in the control step inaccordance with the thickness of the sheet. Therefore, when thethickness of the sheet to be manufactured is changed, tension is morehardly applied to the web to be transported, and thereby it is lesslikely that the web is pulled, and thus is broken or thinned. With this,it is possible to stably manufacture the sheet.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram schematically showing a sheet manufacturingapparatus according to an embodiment.

FIG. 2 is a diagram illustrating an example of a functionalconfiguration of the sheet manufacturing apparatus according to theembodiment.

FIG. 3 is a diagram schematically illustrating a time change in basisweight when changing the basis weight.

FIG. 4 is a diagram schematically illustrating a time change in basisweight when changing the basis weight.

DESCRIPTION OF EMBODIMENTS

Below, various embodiments of the invention will be described. Theembodiments described below are for describing examples of theinvention. The invention is not limited in any way by the followingembodiments, and includes various modifications carried out in a rangenot departing from the gist of the invention. Not all of theconfigurations explained below are indispensable configurations in theinvention.

1. Sheet Manufacturing Apparatus

1.1. Configuration Overview

First, a sheet manufacturing apparatus according to the embodiment willbe described with reference to the drawings. FIG. 1 is a diagramschematically illustrating a sheet manufacturing apparatus 100 accordingto the first embodiment.

The sheet manufacturing apparatus 100 is provided with a supplying unit10, a manufacturing unit 102, and a controller 104, as illustrated inFIG. 1 . The manufacturing unit 102 manufactures a sheet. Themanufacturing unit 102 includes a crushing unit 12, a defibrating unit20, a screening unit 40, a first web forming unit 45, a rotating body49, a mixing unit 50, an accumulation unit 60, a second web forming unit70, a sheet forming unit 80, and a cutting unit 90.

The supplying unit 10 supplies raw materials to the crushing unit 12.The supplying unit 10 is an automatic feeding unit for continuouslyfeeding the raw materials to the crushing unit 12. The raw materialssupplied by the supplying unit 10 include fibers such as recycled pulpand pulp sheets.

The crushing unit 12 cuts the raw material supplied by the supplyingunit 10 into small pieces in air. The shape and size of the small piecesis several cm squared. In the examples in the drawings, the crushingunit 12 includes a crushing blade 14, and it is possible for the fed rawmaterials to be cut by the crushing blade 14. A shredder is used as thecrushing unit 12. The raw material cut by the crushing unit 12 istransferred (transported) to the defibrating unit 20 via a pipe 2 oncereceived by a hopper 1.

The defibrating unit 20 defibrates the raw material cut by the crushingunit 12. Here, the wording “defibrates” refers to untangling the rawmaterial (material to be defibrated) in which a plurality of fibers arebonded into individual fibers. The defibrating unit 20 also has afunction of causing substances such as resin powder bonded to the rawmaterial, ink toner, or blur-preventing agent to be isolated from thefibers.

The material that passes through the defibrating unit 20 is referred toas a “defibrated material”. There are also cases where resin (resin forcausing a plurality of fibers to bond to one another) powder isolatedfrom the fibers when the fibers are untangled, colorants such as ink andtoner, and additives such as bleeding inhibitors and paper strengtheningagents are included in the “defibrated material” in addition to theuntangled defibrated material fibers. The shape of the untangleddefibrated material is string-like or ribbon-like. The untangleddefibrated material may be present in a state of not being entangledwith other untangled fibers (independent state) or may be present in astate being entangled with other untangled defibrated material to form aclump (a state of forming a so-called “lump”).

The defibrating unit 20 performs defibration in a dry manner. Here,performing a treatment such as defibration not in liquid but in air suchas atmosphere is called a dry process. An impeller mill is used as thedefibrating unit 20 in the embodiment. The defibrating unit 20 has thefunction causing an airflow to be generated so as to suction the rawmaterial and discharge the defibrated material. With this, it ispossible for the defibrating unit 20 to suction the raw material alongwith the airflow from an introduction port 22, perform the defibrationtreatment, and transport the defibrated material to the exit port 24with the self-generated airflow. The defibrated material that passesthrough the defibrating unit 20 is transmitted to the screening unit 40via a pipe 3. Note that, as the air flow for causing the defibratedmaterial to be transported from the defibrating unit 20 to the screeningunit 40, an air flow generated by the defibrating unit 20 may beutilized, or an air flow generating device such as a blower may beprovided, and an air flow generated therefrom may be used.

The screening unit 40 introduces a defibrated material defibrated by thedefibrating unit 20 from the introduction port 42 and screens thematerial according to fiber length. The screening unit 40 includes ahousing portion 43 accommodating a drum portion 41 and a drum portion41. A sieve is used as the drum portion 41. The drum portion 41 includesa mesh (filter, screen) and is able to divide fibers or particles (firstscreened material passing through the mesh) that are smaller than thesize of the openings of the mesh and included and fibers, non-defibratedpieces or lumps (second screened material not passing through the mesh)larger than the size of the opening in the mesh. For example, the firstscreened material is transmitted to the mixing unit 50 via the pipe 7.The second screened material is returned to the defibrating unit 20 fromthe exit port 44 via the pipe 8. Specifically, the drum portion 41 is acylindrical sieve that is able to rotatably driven by a motor. A metalmesh of the drum portion 41, an expanded metal in which a perforatedmetal plate is drawn, and a punched metal plate in which holes areformed in a metal plate by a pressing machine or the like are used asthe mesh of the drum portion 41.

The first web forming unit 45 transports the first screened materialpassing through the screening unit 40 to the mixing unit 50. The firstweb forming unit 45 includes a mesh belt 46, a tensioned roller 47, anda suction unit (suction mechanism) 48.

It is possible for the suction unit 48 to suction the first screenedmaterial dispersed in the air after passing through the opening (openingof the mesh) of the screening unit 40 on the mesh belt 46. The firstscreened material is accumulated on the moving mesh belt 46 and formsthe web V. The specific configurations of the mesh belt 46, thetensioned roller 47, and the suction unit 48 are the same as the meshbelt 72, the tensioned roller 74, and the suction mechanism 76 of thesecond web forming unit 70, described later.

The web V is formed in a state of including large volumes of air andbeing softly swelled by passing through the screening unit 40 and thefirst web forming unit 45. The web V accumulated on the mesh belt 46 isfed to the pipe 7 and transported to the mixing unit 50.

The rotating body 49 can cut the web V before transporting the web V tothe mixing unit 50. In the examples of the drawings, the rotating body49 includes a base portion 49 a and a projection 49 b projecting fromthe base portion 49 a. The projection 49 b has a plate shape, forexample. In the examples of the drawings, four projections 49 b areprovided, and the four projections 49 b are provided at even intervals.When the base portion 49 a is rotated in a direction R, the projection49 b can make the base portion 49 a rotated as an axis. When the web Vis cut by the rotating body 49, for example, it is possible to reducefluctuation in the amount of defibrated material per unit time suppliedto the accumulation unit 60.

The rotating body 49 is provided in the vicinity of the first webforming unit 45. In the examples of the drawings, the rotating body 49is provided in the vicinity of (beside the tensioned roller 47 a) thetensioned roller 47 a positioned on the downstream side in the path ofthe web V. The rotating body 49 is provided at a position where theprojection 49 b is in contact with the web V and is not in contact withthe mesh belt 46 on which the web V is accumulated. With this, it ispossible to suppress the mesh belt 46 from being worn (damaged) by theprojection 49 b. The shortest distance between the projection 49 b andthe mesh belt 46 is, for example, in a range of 0.05 mm to 0.5 mm. Themesh belt 46 is the distance at which the web V can be cut without beingdamaged.

The mixing unit 50 mixes the first screened material (first screenedmaterial transported by the first web forming unit 45) passing throughthe screening unit 40 and the additive agent that includes a resin. Themixing unit 50 includes an additive agent supplying unit 52 thatsupplies the additive agent, a pipe 54 that transports the firstscreened material and the additive agent, and a blower 56. In theexamples in the drawings, the additive agent is supplied from theadditive agent supplying unit 52 to the pipe 54 via the hopper 9. Thepipe 54 is contiguous with the pipe 7.

An airflow is generated by the blower 56 in the mixing unit 50, and itis possible to transport the first screened material and the additiveagent while being mixed in the pipe 54. The mechanism by which the firstscreened material and the additive agent are mixed is not particularlylimited, and may be a mechanism that performs stirring with blades thatrotate at high speed, or may be a mechanism that uses the rotation of acontainer such as a V-type mixer.

A screw feeder as illustrated in FIG. 1 , a disk feeder (not shown), orthe like is used as the additive agent supplying unit 52. The additiveagent supplied from the additive agent supplying unit 52 includes aresin for causing the plurality of fibers to bond. At the point in timeat which the resin is supplied, the plurality of fibers is not bonded.The resin is fused when passing through the sheet forming unit 80 andthe plurality of fibers is bonded.

The resin supplied from the additive agent supplying unit 52 is athermoplastic resin or a heat-curable resin, and is an AS resin, an ABSresin, polypropylene, polyethylene, polyvinyl chloride, polystyrene, anacrylic resin, a polyester resin, polyethylene terephthalate,polyphenylene ether, polybutylene terephthalate, nylon, polyamide,polycarbonate, polyacetal, polyphenylene sulfide, polyetherether ketone,or the like. These resins may be used independently or mixed, asappropriate. The additive agent supplied from the additive agentsupplying unit 52 may be in the form of a fiber, or may be in the formof a powder.

The additive agent supplied from the additive agent supplying unit 52may include, according to the type of sheet manufactured, coloringagents for coloring the fibers, coagulation inhibitors for preventingaggregation of the fibers, and flame retardants for making the fibersand the like more difficult to burn, in addition to the resin that bondsthe fibers. The mixture (mixture of the first screened material and theadditive agent) passing through the mixing unit 50 is transmitted to theaccumulation unit 60 via the pipe 54.

The accumulation unit 60 introduces the mixture passing through themixing unit 50 from the introduction port 62, refines the entangleddefibrated material (fibers) and causes the defibrated material todescend while being dispersed in air. The accumulation unit 60 refinesthe entangled resin in a case where the resin of the additive agentsupplied from the additive agent supplying unit 52 is in the form of afiber. In so doing, it is possible for the accumulation unit 60 to causethe mixture to be uniformly accumulated on the second web forming unit70.

The accumulation unit 60 includes a drum portion 61 and a housingportion 63 accommodating the drum portion 61. A cylindrical sieve thatrotates is used as the drum portion 61. The drum portion 61 includes amesh, and causes the fibers of particles (passing through the mesh)included in the mixture passing through the mixing unit 50 and smallerthan the size of the mesh openings to descend. The configuration of thedrum portion 61 is that same as the configuration of the drum portion41.

The “sieve” of the drum portion 61 may have not a function of screeningspecified target materials. That is, the wording “sieve” used as thedrum portion 61 signifies a sieve provided with a mesh, and the drumportion 61 may cause all of the mixture introduced to the drum portion61 to descend.

The second web forming unit 70 accumulates the passing-through materialpassing through accumulation unit 60 and forms the web W. The second webforming unit 70 includes a mesh belt 72, a tensioned roller 74, and asuction mechanism 76.

The mesh belt 72 accumulates the passing-through material passingthrough the openings (openings of the mesh) of the accumulation unit 60while moving. The mesh belt 72 has a configuration in which the meshbelt 72 is tensioned by the tensioned roller 74, and air that does noteasily pass through the passing-through material passes therethrough.The mesh belt 72 moves through the tensioned roller 74 rotating. The webW is formed on the mesh belt 72 by the passing-through material passingthrough the accumulation unit 60 continuously accumulating while themesh belt 72 continuously moves. The mesh belt 72 is made from a metal,a resin, a fabric, a non-woven fabric or the like.

The suction mechanism 76 is provided below (opposite side to theaccumulation unit 60 side) the mesh belt 72. It is possible for thesuction mechanism 76 to cause a downward moving airflow (airflow fromthe accumulation unit 60 to mesh belt 72) to be generated. It ispossible for the mixture dispersed in the air by the accumulation unit60 to be suctioned onto the mesh belt 72 by the suction mechanism 76. Inso doing, it is possible for the discharge speed from the accumulationunit 60 to be increased. It is possible to form a down flow in thedropping path of the mixture by the suction mechanism 76, and it ispossible to avoid the defibrated material and the additive agent beingentangled during dropping.

As above, the web W is formed in a state of including large volumes ofair and being softly swelled by passing through the accumulation unit 60and the second web forming unit 70 (web forming step). The web Waccumulated on the mesh belt 72 is transported to the sheet forming unit80.

In the examples in the drawings, a moisture-adjusting unit 78 thatadjusts the moisture of the web W is provided. It is possible for themoisture-adjusting unit 78 to add water or water vapor to the web W andregulate the ratio of the web W to the water.

The sheet forming unit 80 forms the sheet S by pressurizing and heatingthe web W accumulated on the mesh belt 72. In the sheet forming unit 80,it is possible for the plurality of fibers in the mixture to be bondedto one another via the additive (resin) by applying heat to the mixtureof the defibrated material and the additive agent mixed into the web W.

The sheet forming unit 80 is provided with a pressurizing unit 82 thatpressurizes the web W, and a heating unit 84 that heats the web Wpressurized by the pressurizing unit 82. The pressurizing unit 82 isconstituted by a pair of calender rollers 85 and applies pressure to theweb W. The web W has the thickness reduced by being pressurized, and adensity of the web W is increased. A heating roller (heater roller), ahot press molding machine, a hot plate, a hot air blower, an infraredheating device, or a flash fixing device is used as the heating unit 84.In the examples in the drawings, the heating unit 84 is provided with apair of heating rollers 86. It is possible to form a sheet S whilecontinuously transporting the web W by configuring the heating unit 84as heating rollers 86, compared to a case of configuring the heatingunit 84 as a plate-like press device (plate press device). Here, thecalender roller 85 (pressurizing unit 82) can apply a pressure that ishigher than the pressure applied to the web W to the web W by theheating roller 86 (the heating unit 84). Note that, the number of thecalender rollers 85 and the heating rollers 86 is not particularlylimited.

The cutting unit 90 cut the sheet S formed by the sheet forming unit 80.In the examples in the drawings, the cutting unit 90 includes a firstcutting unit 92 that cut the sheet S in a direction that intersects thetransport direction of the sheet S and a second cutting unit 94 thatcuts the sheet S in a direction parallel to the transport direction. Thesecond cutting unit 94 cuts the sheet S passing through the firstcutting unit 92.

As above, a cut-form sheet S with a predetermined size is formed. Thecut-form sheet S that is cut is discharged to the discharge unit 96.

1.2. Details of Configuration

The sheet manufacturing apparatus 100 is provided with a defibratingunit 20 that defibrates a raw material containing a fiber in air; amixing unit 50 that mixes a defibrated material defibrated by thedefibrating unit 20 and a resin (additive agent) in air; an accumulationunit 60 and a web forming unit (second the web forming unit 70) thatform a web W by accumulating the mixture mixed by the mixing unit 50 ona moving body (mesh belt 72); a transporting unit 110 that transportsthe web W; a sheet forming unit 80 that forms a sheet S from the web W;a setting unit 120 that sets a thickness of the sheet S; and acontroller 104 that controls a moving speed of the moving body (meshbelt 72) and a transporting speed of the web W transported by thetransporting unit 110, in accordance with the thickness of the sheet Sset by the setting unit 120.

Hereinafter, the moving body (mesh belt 72), the transporting unit 110,the setting unit 120, and the controller 104 will be more specificallydescribed. Note that, the defibrating unit 20 and the mixing unit 50 areas described above, and thus a detailed description thereof will not berepeated.

1.2.1. Moving Body

In the sheet manufacturing apparatus 100 of the embodiment, the movingbody is configured to move the accumulated position while accumulatingthe passing-through material passing through the openings (openings ofthe mesh) of the accumulation unit 60. The moving body of the embodimentis the above-described mesh belt 72. The moving body has an accumulationsurface for accumulating the mixtures, and the accumulation surfacecontinuously moves so as to form the web W. The moving speed of theaccumulation surface of the moving body is controlled by the controller104 in accordance with a descending amount of the passing-throughmaterial (mixture) descending from the accumulation unit 60, and thethickness of the sheet S set by the setting unit 120.

In a case where the descending amount of the mixture from theaccumulation unit 60 does not change, the thickness of the web W to beformed is changed by changing the moving speed of the moving body. Inthe embodiment, the thickness of the web W is changed by the movingspeed of the moving body. Here, for example, when the thickness of theweb W is adjusted by increasing the amount of the raw material to besupplied per unit time in the case where the thickness of the sheet S isset to about 2 to 3 times, it is required to enhance the ability of theconfiguration that is located on the upstream side from the moving bodyin the flow direction of the material, thereby resulting in an increasein size of each configuration. However, in the embodiment, the thicknessof the web W is adjusted in a state in which a steady state ismaintained, regarding the configuration located on the upstream sidefrom the moving body in the flow direction of the material. As a result,it is possible to obtain a thick sheet S without increasing the size ofthe configuration of the apparatus.

Note that, in the following description, the accumulation unit 60 thataccumulates the mixtures mixed by the mixing unit 50 on the moving body(the mesh belt 72) and the second web forming unit 70 that forms the webW by accumulating the mixtures may be collectively referred to as a webforming unit.

1.2.2. Transporting Unit

The transporting unit 110 is configured to transport the web W formed bythe web forming unit 70 to the first cutting unit 92 in which the sheetS is cut into a single cut, via the sheet forming unit 80. In theexample of FIG. 1 , three transporting roller pairs of a pair of rollers90 a provided on the upstream side of the first cutting unit 92 and onthe downstream side of the heating roller 86; a pair of rollers 90 bprovided between the first cutting unit 92 and the second cutting unit94; and a pair of rollers 90 c provided on the downstream side of thesecond cutting unit 94 are provided. The roller pair 90 a transports thesheet S to the first cutting unit 92, the roller pair 90 b supports thesheet S at the time of cutting the sheet S by the first cutting unit 92,and transports the sheet S cut by the first cutting unit 92 to thesecond cutting unit 94, and the roller pair 90 c discharges the sheet Scut by the second cutting unit 94 to the discharge unit 96.

In the example in FIG. 1 , the transporting unit 110 is configured toinclude a pair of the calender rollers 85, a pair of the heating rollers86, the roller pair 90 a and the roller pair 90 b. Note that, in theexample in FIG. 1 , the first cutting unit 92 is not included in theconfiguration of the transporting unit 110. The transporting unit 110transports the web W (the continuous sheet S before being a single cut).As described above, since the fibers are not bonded to each other by theresin, the web W is likely to be stretched by applying a tension. Inaddition, since the web W has rigidity (so-called stiffness) smallerthan the sheet S, even in a case of being stretched in a state where thetension is not applied, the web W is stretched or loosened due to itsown weight in some cases.

Note that, the sheet S in the state before cut by the first cutting unit92 (the continuous state before being a single cut) may not becompletely solidified in some cases, and similar to the case of the webW, the sheet may be easily stretched by applying the tension. Inaddition, even in a case of being stretched in a state where the tensionis not applied, the sheet S in the state before cut by the first cuttingunit 92 (the continuous state before being a single cut) is stretched orloosened due to its own weight in some cases. For this reason, in theembodiment, the sheet S in the state before cut by the first cuttingunit 92 (the continuous state before being a single cut) may be handledin the same manner as the above-described web W.

In addition, although not shown, the transporting unit 110 may includeroller pairs other than the above-described roller pairs. Note that, theroller pair is configured to transport the web W (or the continuoussheet S) being sandwiched between the two rollers by rotating therollers.

In each of the roller pairs of the transporting unit 110 of theembodiment, the transporting speed is controlled by the controller 104so as to transport the web W (continuous sheet S) while applyingappropriate tension, which is not to be stretched, to the web W(continuous sheet S).

1.2.3. Setting Unit

The setting unit 120 can set the thickness of the sheet S manufacturedby the sheet manufacturing apparatus 100. The setting unit 120 isprovided in, for example, the controller 104 (refer to FIG. 2 ). Thesetting unit 120 is provided with, for example, an input device such asa touch panel or a switch, and the user can set the thickness of thesheet S by operating the input device. Alternatively, the setting unit120 is provided with a communication interface, and the user can set thethickness of the sheet S from a terminal device such as a computerconnected to the sheet manufacturing apparatus 100. The setting of thethickness of the sheet S by the setting unit 120 may be configured suchthat the user selects from a plurality of predetermined (stored)thicknesses (for example, thin, standard, and thick), or may beconfigured such that the user inputs a numerical value corresponding tothe thickness of the sheet S.

The setting (setting value) of the thickness of the sheet S that can beset by the setting unit 120 can be performed to obtain a discrete valueor a continuous value. Here, setting the discrete value means that, asin the aspect in which the thickness can be changed in increments of 100μm, preferably in increments of 50 μm, further preferably in incrementsof 20 μm, and still further preferably in increments of 10 μm, thesettable setting values are discrete to some extent. Further, settingthe continuous value means that, as in the aspect in which the thicknesscan be changed, for example, in increments of 0.5 μm, preferably inincrements of 0.3 μm, further preferably in increments of 0.1 μm, andstill further preferably in increments of 0.01 μm, the settable settingvalues are substantially continuous as viewed from the thickness of thesheet S to be manufactured.

In a case where the thickness that can be set by the setting unit 120 isthe discrete value, at least two stages of setting can be made. Forexample, settable value of the thickness of the sheet S set by thesetting unit 120 is the first thickness and the second thickness largerthan the first thickness. The controller 104 can switch the thickness ofthe sheet S at a certain timing. For example, switching can be performedwhen the thickness of the sheet S is input to the setting unit 120 bythe user, or after a predetermined number of sheets S are manufactured.

Further, at the time of switching (changing) the thickness of the sheetS, a case of switching the thickness of the sheet S to be larger (forexample, in the case of switching from the first thickness to the secondthickness) and a case of switching the thickness of the sheet S to besmaller (for example, in the case of switching from the second thicknessto the first thickness) occur. Regarding the control in the embodiment,in each of these cases, the moving speed of the moving body and thetransporting speed by the transporting unit 110 are controlled by thecontroller 104 as described below.

1.2.4. Controller

The sheet manufacturing apparatus 100 is controlled by the controller104 so as to manufacture the sheet S having the thickness set by thesetting unit 120. The setting of the thickness of the sheet S set by thesetting unit 120 is referred to by the controller 104.

FIG. 2 is a diagram illustrating an example of a functionalconfiguration of the sheet manufacturing apparatus 100 of theembodiment.

The controller 104 controls the entire (each configuration) of the sheetmanufacturing apparatus 100. The controller 104 of the embodimentcontrols at least the additive agent supplying unit 52, the web formingunit (the second web forming unit 70), the suction mechanism 76, themoving body (the mesh belt 72), the transporting unit 110 (at least apair of calender rollers 85 of the pressurizing unit 82 of the sheetforming unit 80, a pair of heating rollers 86 of the heating unit 84).In addition, the controller 104 obtains the setting of the thickness ofthe sheet S set by the setting unit 120. The thickness of the sheet Sset by the setting unit 120 may be referred to by the controller 104 andstored, and based on the result, the controller 104 may perform thecontrol as follows.

1.3. Control of Moving Speed and Transporting Speed

The controller 104 changes the thickness of the web W by changing themoving speed of the moving body and the transporting speed of thetransporting unit 110 in accordance with the setting of the setting unit120 so as to perform the control of manufacturing the sheet S having thethickness in accordance with the setting.

The thickness of the sheet S is changed in accordance with the thicknessof the web W. The thickness of the web W is changed in accordance withthe moving speed of the moving body (the mesh belt 72). As the movingspeed of the moving body is decreased, the time for accumulating themixtures descending from the accumulation unit 60 is longer, and therebyit is possible to increase the thickness of the web W. In contrast, asthe moving speed of the moving body is increased, the time foraccumulating the mixtures descending from the accumulation unit 60 isshorter, and thereby it is possible to decrease the thickness of the webW.

In the sheet manufacturing apparatus 100 of the embodiment, both of themoving speed of the moving body and the transporting speed by thetransporting unit 110 are changed in accordance with the setting of thesetting unit 120. It is easily understood that when only the movingspeed of the moving body is changed, since a speed difference isgenerated between the moving body and the transporting unit 110 on thedownstream side from the moving body, tension is applied to the web W,and thereby the web W is loosened.

Therefore, when both of the moving speed of the moving body and thetransporting speed by the transporting unit 110 are changed, in a casewhere the thickness of the sheet S to be manufactured is changed,tension is more hardly applied to the web W transported between themoving body and the transporting unit 110, and thereby it is less likelythat the web W is pulled, and thus is broken or thinned. With this, itis possible to stably manufacture the sheet S. Hereinafter, someexamples of such a control will be described.

<Timing of Change of Moving Speed and Transporting Speed>

Regarding the controller 104, in the case where the setting of thesetting unit 120 is changed, the controller 104 may change both of themoving speed of the moving body (the mesh belt 72) and the transportingspeed of the transporting unit 110 at the same time. In this way, evenin a case where the thickness of the sheet S to be manufactured ischanged, it is difficult to cause a transport jam to occur, and it ispossible to more stably manufacture the sheet.

Further, the controller 104 may decrease the moving speed of the movingbody after decreasing the transporting speed of the transporting unit110 when decreasing the moving speed of the moving body and thetransporting speed of the transporting unit 110. That is, in a casewhere the set thickness of the sheet S is changed to be increased, themoving speed of the moving body and the transporting speed of thetransporting unit 110 are decreased; however, at this time, the movingspeed of the moving body on the upstream side may be set to be decreasedafter decreasing the transporting speed of the transporting unit 110 onthe downstream side. With this, it is possible to more reliably preventthe tension from being applied to the web W transported between themoving body and the transporting unit 110, and thereby it is less likelythat the web W is broken or thinned. Therefore, in the case where thethickness of the sheet S to be manufactured is changed (set) so as to bethick, it is possible to more stably manufacture the sheet.

Further, the controller 104 may increase the transporting speed of thetransporting unit 110 after increasing the moving speed of the movingbody when increasing the moving speed of the moving body and thetransporting speed of the transporting unit 110. That is, in a casewhere the set thickness of the sheet S is changed to be decreased, themoving speed of the moving body and the transporting speed of thetransporting unit 110 are increased; however, at this time, thetransporting speed of the transporting unit 110 on the downstream sidemay be set to be increased after increasing the moving speed of themoving body on the upstream side. With this, tension is more hardlyapplied to the web W transported between the moving body and thetransporting unit 110, and thereby it is less likely that the web W ispulled, and thus is broken or thinned. Therefore, in the case where thethickness of the sheet S to be manufactured is changed (set) so as to bethinned, it is possible to more stably manufacture the sheet.

<Order of Change in Transporting Speed>

In the embodiment, the transporting unit 110 includes the pair ofcalender rollers 85 of the pressurizing unit 82 of the sheet formingunit 80, the pair of heating rollers 86 of the heating unit 84, and theroller pair 90 a provided on the upstream side of the first cutting unit92 and the downstream side of the heating roller 86, and the roller pair90 b provided on the downstream side of the first cutting unit 92 andthe upstream side of the second cutting unit 94. In addition, thetransporting unit 110 can include a plurality of roller pairs asdescribed above. That is, it can be said that the transporting unit 110includes the first roller pair and the second roller pair positioned onthe downstream side of the first roller pair. Also in this case, fromthe same viewpoint as above, the following control may be performed.

Note that, in the embodiment, the transporting unit 110 includes a pairof the calender rollers 85, a pair of the heating rollers 86, the rollerpair 90 a, and the roller pair 90 b. For this reason, in the followingdescription, in a case where the first roller pair is set as a pair ofthe calender rollers 85, the second roller pair is a pair of the heatingrollers 86, in a case where the first roller pair is set as a pair ofthe heating rollers 86, the second roller pair is the roller pair 90 a,and in a case where the first roller pair is set as the roller pair 90a, the second roller pair is the roller pair 90 b. In addition, in theaspect that the first roller pair is set as a pair of the calenderrollers 85, and the second roller pair is set as a pair of the heatingrollers 86, the web W is transported; whereas in the case where thefirst roller pair is set as a pair of the heating rollers 86, and thesecond roller pair is set as the roller pair 90 a, and in the case wherethe first roller pair is set as the roller pair 90 a, and the secondroller pair is set as the roller pair 90 b, the continuous sheet S (theweb W) is transported.

The controller 104 may decrease the transporting speed of the firstroller pair after decreasing the transporting speed of the second rollerpair when decreasing the transporting speed of the transporting unit110. That is, in a case where the set thickness of the sheet S ischanged to be increased, the moving speed of the moving body and thetransporting speed of the transporting unit 110 are decreased; however,at the time of decreasing the transporting speed of the transportingunit 110, the transporting speed of the first roller pair on theupstream side may be set to be decreased after decreasing thetransporting speed of the second roller pair on the downstream side.With this, it is possible to more reliably prevent the tension frombeing applied to the web W (or the continuous sheet S), and thereby itis less likely that the web W (or the continuous sheet S) is broken orthinned. Therefore, in the case where the thickness of the sheet S to bemanufactured is changed (set) so as to be thick, it is possible to morestably manufacture the sheet.

In contrast, the controller 104 may increase the transporting speed ofthe second roller pair after increasing the transporting speed of thefirst roller pair when increasing the transporting speed of thetransporting unit 110. That is, in a case where the set thickness of thesheet S is changed to be decreased, the moving speed of the moving bodyand the transporting speed of the transporting unit 110 are increased;however, at the time of increasing the transporting speed of thetransporting unit 110, the transporting speed of the first roller pairon the upstream side may be set to be increased after increasing thetransporting speed of the second roller pair on the downstream side.With this, the tension is hardly applied to the web W (or the continuoussheet S) transported between the first roller pair and the second rollerpair, and thereby it is less likely that the web W (or the continuoussheet S) is pulled, and thus is broken or thinned. Therefore, in thecase where the thickness of the sheet S to be manufactured is changed(set) so as to be thinned, it is possible to more stably manufacture thesheet.

<Mode of Changing the Conveying Speed>

FIG. 3 and FIG. 4 are diagrams schematically illustrating a time changeof the basis weight (weight per unit area) set for changing thethickness of the sheet S. In FIG. 3 and FIG. 4 , it is assumed that thedensity of the raw material is constant, and the change in the basisweight is synonymous with the change in the thickness of the web Wand/or the sheet S. Further, in the embodiment, the change in the basisweight corresponds to the speed of the transporting system (the movingbody and/or the transporting unit 110), and the increase in the basisweight corresponds to decreasing the speed of the transporting system.Note that, the horizontal axes in FIG. 3 and FIG. 4 indicate thedimension of time, but the unit and scale are optional.

As illustrated in FIG. 3 , the controller 104 can stepwisely change eachof the moving speed of the moving body and/or the transporting speed ofthe transporting unit 110. FIG. 3 illustrates an example of a case wherethe thickness of the sheet S to be manufactured is changed to be lager,which is an example of a case where a first thickness corresponds to abasis weight of 250 (g/m²) is changed to the second thicknesscorresponding to a basis weight of 60 (g/m²).

FIG. 3 illustrates an example of stepwisely decreasing the transportingspeed (increasing in terms of basis weight), and as illustrated in FIG.3 , the set basis weight (transporting speed) is changed in a stepshape. The number of steps may be two or more, and the height of onestep, that is, the change amount of the set basis weight (Δy₁) is, forexample, as the basis weight, in a range of 2 (g/m²) to 50 (g/m²), ispreferably in a range of 5 (g/m²) to 30 (g/m²), and is furtherpreferably in a range of 10 (g/m²) to 20 (g/m²). In addition, a periodfor change (hereinafter, referred to as change time Δt) in FIG. 3 is,for example, in a range of 3 seconds to 180 seconds, preferably in arange of 5 seconds to 120 seconds, and further preferably in a range of10 seconds to 60 seconds.

On the other hand, as illustrated in FIG. 4 , the controller 104 canlinearly change the moving speed of the moving body and/or thetransporting speed of the transporting unit 110. FIG. 4 illustrates anexample of a case where the thickness of the sheet S to be manufacturedis changed to be larger, which is an example of a case where a firstthickness corresponds to a basis weight of 250 (g/m²) is changed to thesecond thickness corresponding to a basis weight of 60 (g/m²).

FIG. 4 illustrates an example of linearly decreasing the transportingspeed (increasing in terms of basis weight), and as illustrated in FIG.3 , the set basis weight (transporting speed) is changed in an inclinedstraight line shape. A period for change (hereinafter, referred to aschange time Δt) in FIG. 4 is, for example, in a range of 3 seconds to180 seconds, preferably in a range of 5 seconds to 120 seconds, andfurther preferably in a range of 10 seconds to 60 seconds. In addition,the change amount of the set basis weight (Δy₂) is, for example, as thebasis weight, in a range of 10 (g/m²) to 300 (g/m²), is preferably in arange of 50 (g/m²) to 200 (g/m²), and is further preferably in a rangeof 100 (g/m²) to 200 (g/m²). Therefore, the slope of the inclinedstraight line in the case where the set basis weight is illustrated withrespect to time is Δy₂/Δt, and for example, in a range of 0.6 to 100, ispreferably in a range of 1 to 50, and is further preferably in a rangeof 2 to 50.

The mode of change (stepwise change or linear change) of the movingspeed of the moving body and/or the transporting speed of thetransporting unit 110 by the controller 104 may be configured so thatthe user can select or set, or may be configured so that the controller104 selects in accordance with the change amount in the thickness of thesheet S. In a case of the latter, for example, with reference to a tableor the like stored in advance, it is possible to control the movingspeed of the moving body and/or the transporting speed of thetransporting unit 110.

In this manner, when the controller 104 stepwisely or linearly changeseach of the moving speed of the moving body and/or the transportingspeed of the transporting unit 110, the thickness of the web W isstepwisely or gradually changed. Therefore, the boundary portion wherethe thickness of the web W becomes larger is easily inserted into theroller pair. In addition, when the boundary portion where the thicknessof the web W becomes smaller comes to the roller pair, vibrations andthe like are less likely to occur. As a result, even in the case wherethe thickness of the sheet to be manufactured is changed, it isdifficult to cause transport jam or breakage of the web W or thecontinuous sheet S to occur, and it is possible to more stablymanufacture the sheet.

1.4. Control of Other Configurations in Accordance with Change inTransporting Speed

<Additive Supplying Unit>

As described above, the sheet manufacturing apparatus 100 of theembodiment includes a supplying unit (additive agent supplying unit 52)that supplies an additive to the mixing unit 50. The amount of theadditive supplied by the additive agent supplying unit 52 may be changesin accordance with the thickness of the sheet S (that is, in accordancewith the moving speed of the moving body) set by the setting unit 120.

As described above, when the moving speed of the moving body isdecreased, the thickness of the web W to be formed becomes larger. Here,as the thickness of the web W to be accumulated becomes larger, theadditives (resin) in the material (mixture) may be difficult to come offfrom the web W in some cases. The reason for this is that as thethickness of the web W becomes larger, the path length for detaching theadditive from the web W becomes longer. Therefore, as the moving speedof the moving body is decreased, the proportion of additives (resins)remaining in the web W is increased. In such a case, control may beperformed so as to decrease the amount of the additives (resins)supplied from the additive agent supplying unit 52.

In contrast, when the moving speed of the moving body is decreased, thethickness of the web W to be formed becomes smaller. As the thickness ofthe web W to be accumulated becomes smaller, the additives (resins) inthe material (mixture) may be difficult to come off from the web W insome cases. Therefore, as the moving speed of the moving body isincreased, the proportion of additives (resins) remaining in the web Wis decreased. In such a case, control may be performed so as to increasethe amount of the additives (resins) supplied from the additive agentsupplying unit 52.

On the other hand, when the moving speed of the moving body isdecreased, the time taken for suction by the suction mechanism 76becomes longer, so that the additives (resins) are easily come off fromthe web W in some cases. Therefore, as the moving speed of the movingbody is decreased, the proportion of additives (resins) remaining in theweb W is decreased. In such a case, control may be performed so as toincrease the amount of the additives (resins) supplied from the additiveagent supplying unit 52.

On the other hand, when the moving speed of the moving body isincreased, the time taken for suction by the suction mechanism 76becomes shorter, so that the additives (resins) are not easily come offfrom the web W in some cases. Therefore, as the moving speed of themoving body is increased, the proportion of additives (resins) remainingin the web W is increased. In such a case, control may be performed soas to decrease the amount of the additives (resins) supplied from theadditive agent supplying unit 52.

The amount of additives remaining on the web W is changed due to, forexample, the thickness of the web W, the size and properties of theadditive, and the suction force by the suction mechanism 76, and thus,as described above, it is desirable to appropriately control the amountof additives supplied from the additive supply unit 52.

In this manner, even in a case where the thickness of the sheet S to bemanufactured is changed, it is possible to stabilize the amount of theadditive agent (abundance) in the sheet S to be manufactured. With this,the mechanical strength of the sheet to be manufactured can bestabilized.

<Suction Unit>

As described above, the sheet manufacturing apparatus 100 of theembodiment includes the suction mechanism 76 (the suction unit) thatsuctions a mixture dispersed in the air by the accumulation unit 60 ontothe mesh belt 72 (the moving body). The suction force of the suctionunit may be changes in accordance with the thickness of the sheet S(that is, in accordance with the moving speed of the moving body) set bythe setting unit 120.

As described above, when the moving speed of the moving body isincreased, the thickness of the web W to be formed becomes smaller.Here, as the thickness of the web W to be accumulated becomes smaller,the additives (resins) in the material (mixture) may be difficult tocome off from the web W in some cases. The reason for this is that asthe thickness of the web W becomes smaller, the path length fordetaching the additive from the web W becomes shorter. Therefore, as themoving speed of the moving body is increased, the proportion ofadditives (resins) remaining in the web W is decreased. In such a case,control may be performed so as to decrease the suction force of thesuction mechanism 76. On the other hand, in a case where the movingspeed of the moving body is decreased, control may be performed so as toincrease the suction force of the suction mechanism 76.

On the other hand, when the moving speed of the moving body isincreased, the time taken for suction by the suction mechanism 76becomes shorter, so that the additives (resins) are not easily come offfrom the web W in some cases. Therefore, as the moving speed of themoving body is increased, the proportion of additives (resins) remainingin the web W is increased. In such a case, control may be performed soas to increase the suction force of the suction mechanism 76. On theother hand, in a case where the moving speed of the moving body isdecreased, control may be performed so as to decrease the suction forceof the suction mechanism 76.

The amount of additives remaining on the web W is changed due to, forexample, the thickness of the web W, the size and properties of theadditive, and thus, as described above, it is desirable to appropriatelycontrol the suction force by the suction mechanism 76.

In this manner, even in a case where the thickness of the sheet S to bemanufactured is changed, it is possible to stabilize the amount of theadditive agent (abundance) in the sheet S to be manufactured. With this,the mechanical strength of the sheet to be manufactured can bestabilized.

1.5. Control when Apparatus is Stopped

The sheet manufacturing apparatus 100 of the embodiment can be startedand stopped at an appropriate timing by a user's operation and/or atimer. On the other hand, as described above, settable value of thethickness of the sheet S set by the setting unit 120 of the sheetmanufacturing apparatus 100 is the first thickness and the secondthickness larger than the first thickness. Here, the first thickness is,for example, the thickness of a PPC paper generally used in offices. Inthe embodiment, as described above, the thickness of the sheet havingthe basis weight of 60 (g/m²) is set as the first thickness, and thethickness of the sheet having the basis weight of 250 (g/m²) is set asthe second thickness.

Here, the controller 104 may stop the sheet manufacturing apparatus 100after setting the moving speed of the moving body and the transportingspeed of the transporting unit 110 to a speed in accordance with therelatively small first thickness. For example, the apparatus is stoppedwhen the moving speed of the moving body and the transporting speed ofthe transporting unit 110 are set to be the speed in accordance with thefirst thickness, the continuous sheet S having the first thickness isformed, and the sheet S is transported to the cutting unit 90.

In this case, as the sheet manufacturing apparatus 100 is stopped, theweb W remains between the moving body and the roller pair of thetransporting unit 110 in a case where the moving body and thetransporting unit 110 are stopped. In a case of thick web W which isstretched and stopped between the roller pair when the apparatus isstopped, since the fibers are not bonded to each other by the resin,even in a case of being stretched in a state where the tension is notapplied, the web W is stretched or loosened due to its own weight insome cases.

For this reason, when the controller 104 stops the sheet manufacturingapparatus 100 after setting the moving speed of the moving body and thetransporting speed of the transporting unit 110 to a speed in accordancewith the relatively small first thickness, it is possible to reduce theextension of the web W due to the weight of the apparatus itself. Thatis, since the thickness of the web W remaining between the roller pairwhen at the time of stop is the first thickness which is relativelythin, the web W is less likely to be loosened, and broken under its ownweight. For example, it is possible to stably start the sheetmanufacturing apparatus 100 at the time of restart. In the aboveexamples, the sheet manufacturing apparatus 100 is stopped after settingthe speed in accordance with the first thickness; however, the sheetmanufacturing apparatus 100 may be stopped after setting the speed inaccordance with the thickness at which the web W is not broken due toits own weight. For example, the apparatus may be stopped at a speed inaccordance with the thickness smaller than the first thickness, or maybe stopped at a speed in accordance with the thickness larger than thefirst thickness and smaller than the second thickness.

2. Sheet Manufacturing Method

A sheet manufacturing method includes a defibrating step of defibratinga raw material containing a fiber in air; a mixing step of mixing adefibrated material defibrated in the defibrating step and a resin inair; a web forming step of forming a web by accumulating the mixturemixed in the mixing step on a moving body; a transporting step oftransporting the web; a sheet forming step of forming a sheet from theweb; a setting step of setting a thickness of the sheet; and a controlstep of controlling a moving speed of the moving body and a transportingspeed of the web in the transporting step, in accordance with thethickness of the sheet set in the setting step.

These steps can be performed by the above-described sheet manufacturingapparatus 100. The defibrating step, the mixing step, the web formingstep, the sheet forming step, the setting step, and the control step canbe performed by the above-described defibrating unit 20, the mixing unit50, the web forming unit 70, the sheet forming unit 80, the setting unit120, and the controller 104. The details of these steps are the same asthose described in the above-described sheet manufacturing apparatus,and thus detailed description will not be repeated.

According to the sheet manufacturing method of the embodiment, both ofthe moving speed of the moving body in the web forming step and thetransporting speed of the web W by the transporting step are controlledin accordance with the thickness of the sheet S set in the setting step.Therefore, for example, in a case where the thickness of the sheet S tobe manufactured is set to be larger, tension is more hardly applied tothe web W transported between the web forming step and the transportingstep, and thereby it is less likely that the web W is pulled, and thusis broken or thinned. In addition, for example, in a case where thethickness of the sheet S to be manufactured is set to be smaller,tension is more hardly applied to the web W transported between the webforming step and the transporting step, and thereby it is less likelythat the web W is pulled, and thus is broken or thinned. With this, itis possible to stably manufacture the sheet S.

3. Other Provisions

Although the sheet manufacturing apparatus and the sheet manufacturingmethod of the embodiment use no or only a small amount of water, it ispossible to manufacture the sheet while adding water, as appropriate,with the object of adjusting the moisture or the like, through sprayingor the like as necessary.

In the specification, the phrasing “uniform” indicates, in a case ofuniform dispersion or mixing, the relative positions where one componentis present with respect to the other component are even in the entiresystem or are the same or substantially equal in each part of the systemto one another in a substance able to define a component with two typesor more or two phases or more. Uniformity of coloring or uniformity oftone indicates an even concentration without tinting of the color whenthe sheet is seen in plan view.

In the specification, phrasing such as “uniform”, “same”, “evenintervals” and the like are used to indicate that density, distance,measurement or the like are the same. Although it is desirable thatthese are equal, because being made completely equal is difficult, thewording includes being shifted by the cumulative errors or variationswithout the values being equal.

The invention is not limited to the above-described embodiments, andvarious modifications are possible. For example, the invention includesa configuration substantially the same as that described in theembodiment (for example, a configuration having the same function,method, and result, or a configuration having the same object andeffect). Further, the invention includes a configuration in whichnon-essential parts of the configuration described in the embodiment arereplaced. Further, the invention includes a configuration that canachieve the same effects as the configuration described in theembodiment, or a configuration that can achieve the same object. Inaddition, the invention includes a configuration in which a well-knowntechnique is added to the configuration described in the embodiment.

REFERENCE SIGNS LIST

-   -   1 . . . HOPPER    -   2, 3, 4, 5, 7, 8 . . . PIPE    -   9 . . . HOPPER    -   10 . . . SUPPLYING UNIT    -   12 . . . CRUSHING UNIT    -   14 . . . CRUSHING BLADE    -   20 . . . DEFIBRATING UNIT    -   22 . . . INTRODUCTION PORT    -   24 . . . EXIT PORT    -   40 . . . SCREENING UNIT    -   41 . . . DRUM PORTION    -   42 . . . INTRODUCTION PORT    -   43 . . . HOUSING PORTION    -   44 . . . EXIT PORT    -   45 . . . FIRST WEB FORMING UNIT    -   46 . . . MESH BELT    -   46 a . . . ACCUMULATION SURFACE    -   47, 47 a . . . TENSIONED ROLLER    -   48 . . . SUCTION UNIT    -   49 . . . ROTATING BODY    -   49 a . . . BASE PORTION    -   49 b . . . PROJECTION    -   50 . . . MIXING UNIT    -   52 . . . ADDITIVE AGENT SUPPLYING UNIT    -   54 . . . PIPE    -   56 . . . BLOWER    -   60 . . . ACCUMULATION UNIT    -   61 . . . DRUM PORTION    -   62 . . . INTRODUCTION PORT    -   63 . . . HOUSING PORTION    -   70 . . . SECOND WEB FORMING UNIT    -   72 . . . MESH BELT    -   74 . . . TENSIONED ROLLER    -   76 . . . SUCTION MECHANISM    -   78 . . . MOISTURE-ADJUSTING UNIT    -   80 . . . SHEET FORMING UNIT    -   82 . . . PRESSURIZING UNIT    -   84 . . . HEATING UNIT    -   85 . . . CALENDER ROLLER    -   86 . . . HEATING ROLLER    -   90 . . . CUTTING UNIT    -   90 a, 90 b, 90 c . . . ROLLER PAIR    -   92 . . . FIRST CUTTING UNIT    -   94 . . . SECOND CUTTING UNIT    -   96 . . . DISCHARGE UNIT    -   100 . . . SHEET MANUFACTURING APPARATUS    -   102 . . . MANUFACTURING UNIT    -   104 . . . CONTROLLER    -   110 . . . TRANSPORTING UNIT    -   120 . . . SETTING UNIT    -   S . . . SHEET    -   V . . . WEB    -   W . . . WEB

What is claimed is:
 1. A sheet manufacturing method comprising:defibrating a raw material containing a fiber in air; mixing a resin anda defibrated material defibrated in the defibrating of the raw materialin air; forming a web by accumulating the mixture mixed in the mixing ona moving body; transporting the web on a downstream side of the movingbody in a transporting direction of the web, after the forming of theweb; forming a sheet from the web; setting a thickness of the sheet; andcontrolling a moving speed of the moving body and controlling atransporting speed of the web in the transporting of the web, inaccordance with the thickness of the sheet set in the setting of thethickness.
 2. The sheet manufacturing method according to claim 1,wherein in the controlling of the moving speed and the transport speed,the moving speed of the moving body and the transporting speed of thetransporting unit change at the same time.
 3. The sheet manufacturingmethod according to claim 1, wherein in the controlling of the movingspeed and the transport speed, the moving speed of the moving bodydecreases after decreasing the transporting speed of the transportingunit.
 4. The sheet manufacturing method according to claim 1, wherein inthe controlling of the moving speed and the transport speed, the movingspeed of the moving body increases after increasing the transportingspeed of the transporting unit.
 5. The sheet manufacturing methodaccording to claim 1, wherein the transporting of the web is performedby a first roller pair and a second roller pair that is positioned onthe downstream side of the first roller pair.
 6. The sheet manufacturingmethod according to claim 5, wherein in the controlling of the movingspeed and the transport speed, the transporting speed of the firstroller pair decreases after decreasing the transporting speed of thesecond roller pair.
 7. The sheet manufacturing method according to claim5, wherein in the controlling of the moving speed and the transportspeed, the transporting speed of the first roller pair increases afterincreasing the transporting speed of the second roller pair.
 8. Thesheet manufacturing method according to claim 1, wherein in thecontrolling of the moving speed and the transport speed, each of themoving speed of the moving body and the transporting speed of thetransporting unit changes stepwise.
 9. The sheet manufacturing methodaccording to claim 1, wherein in the controlling of the moving speed andthe transport speed, each of the moving speed of the moving body and thetransporting speed of the transporting unit changes linearly.